Stacked plate heat exchanger in particular an oil cooler for motor vehicles

ABSTRACT

The invention relates to a stacked plate heat exchanger ( 1 ), in particular, an oil cooler for motor vehicles, made up into an assembly from alternating dished plates and baffle sheets ( 3 ), stacked one on top of and inside the other, each comprising first and second through openings ( 7, 8 ), for the formation of distribution and collector channels, which are welded together to form said first and second flow channels, whereby the baffle sheets ( 3 ) form a stay between the stacked plates and the assembly is enclosed by a base plate ( 4 ) and a cover plate ( 5 ).

The invention relates to a stacked plate heat exchanger, in particularan oil cooler for motor vehicles, in particular according to thepreamble of patent claim 1.

Stacked plate heat exchangers, in particular oil/coolant coolers forinternal combustion engines of motor vehicles, are known from variousdocuments of the applicant, for example from DE-A 43 14 808, DE-A 195 11991 or DE-A 197 50 748. The stacked plate heat exchangers, also calledplate heat exchangers, comprise a multiplicity of trough-shaped stackingplates, and if appropriate turbulence inserts, which are placed into oneanother and stacked to form a block. The stacking plates are usuallyrectangular in shape—though circular stacking plates are also known—withfour passage openings, two for each flow medium, which are arranged inthe corner regions of the stacking plates. The stacking plates form flowducts together with the turbulence inserts, while the passage openingsform distribution or collection ducts which are connected either to thefirst or to the second flow medium. The two different flow ducts, thatis to say the different flow media, are partitioned by virtue of thefact that two of the passage openings are in each case arranged in araised annular stamped formation which is soldered to the adjacentstacking plate which is planar in this region. The turbulence insertsboth increase the heat transfer capacity, in particular that of oil, andserve as a tie rod against the inner pressure which builds up duringoperation and can be approximately 6 to 10 bar in oil coolers. Stackedplate heat exchangers for cooling exhaust gas or charge air are alsoknown, for example from DE-A 195 11 991 cited above.

The outermost, that is to say the upper and the lower flow ductsconstitute a problem when dimensioning the stacked plate heatexchangers, since they are considered the weakest link with regard tothe inner pressure loading. While there is pressure equalization in thecase of the inwardly situated flow ducts, this is not the case for theouter flow ducts. In addition, in the region of the passage openings,the tie rod action of the metal turbulence plates is adversely affectedon account of the cut shape of the metal turbulence plates and thestamped formations in the stacking plates, so that the full innerpressure resistance is not obtained here. To solve this problem, theupper and lower closing plates have been provided with a relativelylarge wall thickness or—as described in DE-A 197 11 258—with astrengthening plate between the lowest stacking plate and a base plate.Strengthening plates of this type or increased wall thicknesses lead toadditional weight and to increased costs.

It is an object of the present invention to improve a stacked plate heatexchanger of the type mentioned in the introduction with regard to itsstrength, in particular its inner pressure resistance, withoutsignificantly increasing the weight.

This object is achieved by means of the features of patent claim 1.According to the invention, a thin intermediate metal plate is insertedbetween the uppermost turbulence insert and the cover plate, whichintermediate metal plate has the cut shape and the hole pattern of theturbulence insert and is soldered to the latter and to the cover plate.This brings about the advantage that, in the region of the passageopenings or of the distribution or collection ducts in particular,higher inner pressure resistance is obtained in the region of saidopenings. The uppermost turbulence insert is soldered at its upper sideto the intermediate metal plate, and the intermediate metal plate isadvantageously also soldered to the cover plate, producing a tie rodaction which results in an increase in strength.

In a further embodiment of the invention, the cover plate has a stampedformation in the region of the passage openings in a concentricarrangement, which stamped formation is directed outward in such a waythat a hollow space in the form of an annular gap is produced betweenthe intermediate metal plate and the cover plate. This annular gap givesrise to pressure equalization on the intermediate metal plate in thecircumferential region of the passage opening. This results in theadvantage of increased inner pressure resistance, in particular in theregion of the passage openings. On account of its low wall thickness ofa few tenths of a millimeter, the intermediate metal plate practicallyconstitutes an almost weight-neutral measure for increasing the strengthof the stacked plate heat exchanger.

Further solutions according to the invention are presented by claim 7.

One exemplary embodiment of the invention is described in more detail inthe following and is illustrated in the drawing, in which:

FIG. 1 shows the construction of a stacked plate oil cooler in apartially exploded illustration,

FIG. 2 shows one stacking plate of the stacked plate oil cooler fromFIG. 1,

FIG. 3 shows a metal turbulence plate,

FIG. 4 shows the metal turbulence plate from FIG. 3 inserted into thestacking plate from FIG. 2 and

FIG. 5 shows a cross-section through the uppermost part of the stackedplate oil cooler having an intermediate metal plate.

FIG. 1 shows the construction of a stacked plate oil cooler 1 which isconstructed from a multiplicity of stacking plates 2 and metalturbulence plates 3 (turbulence inserts) arranged between said stackingplates 2. The stacked plate oil cooler 1 is closed off by means of abase plate 4 and a cover plate 5. An intermediate metal plate 6, whichis described in more detail in conjunction with the description of FIG.5, is inserted between the uppermost metal turbulence plate 3 and thecover plate 5. Connections for the oil and a liquid coolant are arrangedin the base plate 4, but cannot be seen or are not illustrated—theycorrespond to the prior art cited in the introduction. In contrast, thecover plate 5 is closed; it has, as is described later, stampedimpressions 10, 12.

FIG. 2 shows one of the stacking plates 2 which is trough-shaped and hasa substantially planar base 2 a, a continuously encircling raised edge 2b, first passage openings 7 and second passage openings 8 which are eacharranged in the corner regions of the approximately rectangular stackingplate 2. While the first passage openings 7 are arranged in the plane ofthe base 2 a, the second passage openings 8 are raised relative to thebase 2 a and are arranged in an annular stamped formation 9. Whenstacked and soldered on top of one another, the first passage openings 7and the second passage openings 8 form distribution and collection ducts(7 a, 8 a, cf. FIG. 5) for the first flow medium, for example engine oilof an internal combustion engine of a motor vehicle, and the second flowmedium, for example the coolant of a cooling circuit (not illustrated)of the internal combustion engine.

FIG. 3 shows one of the turbulence inserts 3 which is inserted into thestacking plate 2 and therefore has the same outer cut shape and the samehole pattern with first passage openings 7 and second passage openings8′ which correspond in diameter to the annular stamped formations 9 andare therefore larger than the passage openings 8. The metal turbulenceplate 3 is known from the prior art and serves to improve the heattransfer, in particular on the oil side, and to increase the innerpressure resistance by means of a tie rod effect.

FIG. 4 shows the stacking plate 2 with the metal turbulence plate 3inserted, the upper side of the annular stamped formations 9 beinguncovered. Further stacking plates and metal turbulence plates arestacked on top of one another in an alternating fashion on said stackingplate 2 with the metal turbulence plate 3 inserted, as a result of whichflow ducts for the oil and the coolant are formed in an alternatingfashion, which flow ducts are separated from one another by means of thesoldering of the stacking plates.

FIG. 4 shows a flow duct, which is covered at the top, for the mediumoil, the oil flowing into the flow duct via one of the two passageopenings 7, passing through said flow duct approximately diagonallythrough the metal turbulence plate 3, and flowing out again via theother passage opening 7 which is situated diametrically opposite. Theoil flow duct is covered by a stacking plate (not illustrated) which hasannular stamped formations in the region of the first passage openings 7and is flat in the region of the passage openings 8, so that solderingis carried out in the region of the annular face 9.

FIG. 5. shows a cross-section through the uppermost region of thestacked plate oil cooler from FIG. 1, identical reference signs beingused for identical parts. The section passes transversely through thetwo front passage openings 8, 7 which are arranged one above the otherand form a distribution or collection duct 8 a for the coolant and adistribution or collection duct 7 a for the oil. Of the entire stack,only the uppermost stacking plate 2 is illustrated completely, whichuppermost stacking plate 2 has the annular stamped formation 9 in theregion of the passage opening 8. The passage opening 7 is arranged, atthe right-hand side of the stacking plate 2 in the drawing, in theplanar base region 2 a, that is to say offset in height relative to thepassage opening 8. A metal turbulence plate 3 is placed on the baseregion 2 a, which metal turbulence plate 3 has the cutout 8′ in theregion of the stamped formation 9 and has the cutout 7 (cf. FIG. 3) inthe region of the passage opening 7. The intermediate metal plate 6 (cf.FIG. 1) is arranged above the metal turbulence plate 3 and has the samehole pattern as the stacking plate 2. Said intermediate metal plate 3 isrelatively thin and has, for example, a wall thickness of from 0.1 to0.5 mm, inclusive of solder plating at each side. The cover plate 5,which closes off the stacked plate oil cooler 1 at the top, is placedonto the intermediate metal plate 6, the cover plate 5 being closed inthis exemplary embodiment, that is to say it closes off all the firstand second passage openings 7, 8 (four in total). The cover plate 5,intermediate metal plate 6, metal turbulence plate 3 and the uppermoststacking plate 2 are soldered to one another at their contact points. Inthe region of the passage openings 8, the cover plate 5 hasspherical-cap-like inwardly directed stamped impressions 10 whichproject into the distribution collection ducts 8a. In the region of thepassage openings 7, the cover plate 5 has outwardly directed stampedformations 11 which each have a spherical-cap-like, inwardly directedstamped impression 12 in their central region. The distribution orcollection duct 7 a has a diameter D1 and extends through the metalturbulence plate 3 and the intermediate metal plate 6. A hollow space inthe form of an annular gap 13 is formed between the stamped formation 11and the intermediate metal plate 6, which hollow space has an outerdiameter D2 which is larger than the diameter D1 of the distribution orcollection duct 7 a, approximately 10 mm larger. The annular gap 13communicates with the duct 7 a, as a result of which pressureequalization with the adjacent oil flow duct (not illustrated) isproduced. The intermediate metal plate 6 is therefore relieved of loadin the region of the annular face between the diameters D2—D1. Thepressure forces arising from the inner pressure are guided directly intothe closing plate 5 outside the diameter region D2 via the combinationof the soldered metal turbulence plate 3 and the intermediate metalplate 6. The metal turbulence plate 3 therefore acts in conjunction withthe intermediate metal plate 6 as a sandwich component with relativelyhigh pressure resistance and bending strength.

1. A stacked plate heat exchanger, in particular oil cooler for motorvehicles, comprising trough-shaped stacking plates and metal turbulenceplates which are stacked onto and into one another in an alternatingfashion to form a block and each have first and second passage openingsfor forming distribution and collection ducts and are soldered to oneanother to form first and second flow ducts, the metal turbulence platesforming tie rods between the stacking plates and the block being closedoff by means of a base plate and a cover plate, characterized in that athin intermediate metal plate, which has the hole pattern of the metalturbulence, plate is arranged between the uppermost metal turbulenceplate and the cover plate and is soldered both to the metal turbulenceplate and to the cover plate.
 2. The stacked plate heat exchanger asclaimed in claim 1, wherein the stacking plates each have asubstantially planar face and annular stamped formations, and in thatthe first passage openings are arranged in the substantially planar faceand the second passage openings are arranged, such that they are raised,in the annular stamped formations and are at least partially closed offoutwardly by means of the cover plate, and in that an outwardly directedstamped formation is arranged in the cover plate concentrically withrespect to the first passage openings, and an annular gap is leftbetween the stamped formation and the thin intermediate metal plate. 3.The stacked plate heat exchanger as claimed in claim 1, wherein thecover plate is soldered to the intermediate metal plate in the region ofthe second passage openings.
 4. The stacked plate heat exchanger asclaimed in claim 1, wherein the intermediate metal plate has a wallthickness of from 0.1 to 0.5 mm and is preferably solder-plated at eachside.
 5. The stacked plate heat exchanger as claimed in claim 1, whereinthe passage openings have an inner diameter D1 and the stamped formationhas an inner diameter D2, D2 being approximately 10 mm larger than D1.6. The stacked plate heat exchanger as claimed in claim 1, wherein thecover plated has concentric, spherical-cap-shaped stamped impressions inthe region of the passage openings.
 7. The stacked plate heat exchangerin a variation of claim 1, wherein an intermediate metal plate havingthe hole pattern of the metal turbulence plate is arranged between atleast one metal turbulence plate and a stacking plate and/or between ametal turbulence plate and a cover-plate and/or between a metalturbulence plate and a base plate, and is soldered both to the metalturbulence plate and to the cover plate, the stacking plate and/or thebase plate.
 8. The stacked plate heat exchanger as claimed in claim 2,wherein the cover plate is soldered to the intermediate metal plate inthe region of the second passage openings.
 9. The stacked plate heatexchanger as claimed in claim 2, wherein the intermediate metal platehas a wall thickness of from 0.1 to 0.5 mm and is preferablysolder-plated at each side.
 10. The stacked plate heat exchanger asclaimed in claim 3, wherein the intermediate metal plate has a wallthickness of from 0.1 to 0.5 mm and is preferably solder-plated platedat each side.
 11. The stacked plate heat exchanger as claimed in claim2, wherein the passage openings have an inner diameter D1 and thestamped formation has an inner diameter D2, D2 being approximately 10 mmlarger than D1.
 12. The stacked plate heat exchanger as claimed in claim3, wherein the passage openings have an inner diameter D1 and thestamped formation has an inner diameter D2, D2 being approximately 10 mmlarger than D1.
 13. The stacked plate heat exchanger as claimed in claim4, wherein the passage openings have an inner diameter D1 and thestamped formation has an inner diameter D2, D2 being approximately 10 mmlarger than D1.
 14. The stacked plate heat exchanger as claimed in claim2, wherein the cover plate has concentric, spherical-cap-shaped stampedimpressions in the region of the passage openings.
 15. The stacked plateheat exchanger as claimed in claim 3, wherein the cover plate hasconcentric, spherical-cap-shaped stamped impressions in the region ofthe passage openings.
 16. The stacked plate heat exchanger as claimed inclaim 4, wherein the cover plate has concentric, spherical-cap-shapedstamped impressions in the region of the passage openings.
 17. Thestacked plate heat exchanger as claimed in claim 5, wherein the coverplate has concentric, spherical-cap-shaped stamped impressions in theregion of the passage openings.